Risk Of Phosphorus Loss Research Articles

Adsorption and risk of phosphorus loss in soils in Amazonia

Low availability of phosphorus in Amazonian soils is the result of both naturally occurring low levels and adsorption processes in the soil. These factors encourage the use of intensive phosphate fertilizations to increase productivity, which, in turn, increases P saturation and contamination risk. This study was designed to determine the adsorption capacity, as well as the risk of P loss and contamination of water bodies by P in Amazonian soils. Eleven soils located in zones free from any alteration were selected in order to set parameters for natural conditions for the local soils. Adsorption experiments were carried out in CaCl2 solution 0.01 mol L−1, containing 0 to 200 mg L−1 of P in the form of KH2PO4. The phosphorus sorption index (PSI) was determined, and soluble and available forms of P were extracted in water, Mehlich-1, Olsen, and CaCl2 solutions. The phosphorus saturation degree (PSD) was obtained by extraction with acid solution of ammonium oxalate. PSI was lower in the soil GL (Eutric Gleysol) and higher for NT (Rhodic Nitisol), while the maximum adsorption capacity (Smax) was lower in the soil AR (Ferralic Arenosol) and higher in AC1 (Haplic Acrisol 1). The PSD was higher in AT (Hortic Anthrosol) which also showed higher values of soluble and available P, while lower saturation values were observed in FR2 (Xanthic Ferralsol), FR4 (Rhodic Ferralsol), Haplic Acrisol 2, and Eutric Gleysol (< 5%). These soils presented low to medium maximum adsorption capacity and low P saturation; however, Ferralic Arenosol soil showed a high risk of P loss, making P management very difficult. Similarly, Hortic Anthrosol showed high susceptibility to P loss.

Evaluating the risk of phosphorus loss with a distributed watershed model featuring zero-order mobilization and first-order delivery

Many semi-distributed models that simulate pollutants' losses from watersheds do not handle well detailed spatially distributed and temporal data with which to identify accurate and cost-effective strategies for controlling pollutants issuing from non-point sources. Such models commonly overlook the flow pathways of pollutants across the landscape. This work aims at closing such knowledge gap by developing a Spatially and Temporally Distributed Empirical model for Phosphorus Management (STEM-P) that simulates the daily phosphorus loss from source areas to receiving waters on a spatially-distributed grid-cell basis. STEM-P bypasses the use of complex mechanistic algorithms by representing the phosphorus mobilization and delivery processes with zero-order mobilization and first-order delivery, respectively. STEM-P was applied to a 217km2 watershed with mixed forest and agricultural land uses situated in southwestern China. The STEM-P simulation of phosphorus concentration at the watershed outlet approximated the observed data closely: the percent bias (Pbias) was −7.1%, with a Nash-Sutcliffe coefficient (ENS) of 0.80 on a monthly scale for the calibration period. The Pbias was 18.1%, with a monthly ENS equal to 0.72 for validation. The simulation results showed that 76% of the phosphorus load was transported with surface runoff, 25.2% of which came from 3.4% of the watershed area (classified as standard A critical source areas), and 55.3% of which originated from 17.1% of the watershed area (classified as standard B critical source areas). The standard A critical source areas were composed of 51% residences, 27% orchards, 18% dry fields, and 4% paddy fields. The standard B critical source areas were mainly paddy fields (81%). The calculated spatial and temporal patterns of phosphorus loss and recorded flow pathways identified with the STEM-P simulations revealed the field-scale critical source areas and guides the design and placement of effective practices for non-point source pollution control and water quality conservation.

Nano-cerium oxide functionalized biochar for phosphate retention: preparation, optimization and rice paddy application

In this study, nano-cerium oxide functionalized maize straw biochar (Ce-MSB) was prepared and utilized to remove P from agricultural wastewater. Response Surface Model was applied to optimize the operating conditions. Moreover, Ce-MSB was applied to actual rice paddy column for the first time. Response Surface Model (RSM) showed higher materials ratio had positive effect on PO43− adsorption capacity, while higher pyrolysis temperature had negative effect. The maximum adsorption capacity of Ce-MSB for PO43− was 78 mg g−1, implying that Ce-MSB was an effective functionalized adsorbent for P removal. Paddy soil column experiment showed that application of Ce-MSB decreased total phosphorus concentration of surface water by 27.33% and increased total phosphors (TP) content of top soil by 7.22%. Further, Ce-MSB tends to increase rice plant height and leaf area. Therefore, Ce-MSB can be used as a promising functionalized biochar to reduce the risk of phosphorus loss from paddy field surface running water.

Parameters for Site-Specific Soil Phosphorus Loss Modeling from Soil Test Data

This 4-page fact sheet is part of the Soil Phosphorus Storage Capacity (SPSC) for Phosphorus Risk Assessment and Management series. This series is intended for use by those who are interested in management practices and policies that minimize the risk of phosphorus loss from soils. Written by Biswanath Dari, Vimala D. Nair, and Willie G. Harris and published by the Department of Soil and Water Sciences, February 2017. SL442/SS656: Parameters for Site-Specific Soil Phosphorus Loss Modeling from Soil Test Data (ufl.edu)

Degree of phosphorus saturation threshold for minimizing P losses by runoff in cropland soils of Southern Brazil

Abstract The objective of this work was to assess the risk of phosphorus losses by runoff through an index based on the degree of P saturation (DPS), in cropland soils of Southern Brazil. Sixty-five highly representative cropland soils from the region were evaluated. Three labile P forms were measured (Mehlich-1, Mehlich-3, and ammonium oxalate), and four P sorption indexes were tested (phosphorus single sorption point and Fe+Al determined with the three extractors). Water-extractable P (WEP) was used as an index of P susceptibility to losses by surface runoff. The DPS was determined from the ratio between labile P and each sorption index. DPS values obtained from the ratio between Mehlich-1 P and the single P sorption point ranged from 1 to 25%, whereas those from Mehlich-1 P and Fe+Al (ammonium oxalate) ranged from 1 to 55%. All DPS types were highly correlated with WEP. From a practical stand point, the DPS obtained with both P and Fe+Al extracted with Mehlich-1 can be used to estimate the risk of P losses by runoff in soils of Southern Brazil.

Phosphorus source coefficient determination for quantifying phosphorus loss risk of various animal manures

Quantification of phosphorus (P) loss risk of animal manures is essential to scientifically sound P risk assessment and environmental friendly nutrient management, but has faced significant challenges due to the shortage of appropriate techniques. This study was conducted to determine P source coefficients (PSC) for quantifying differential P loss risk of various manures relative to soluble chemical fertilizer. After 2-d, 2-week, 8-week, and 26-week soil incubations with various manures, P-amended soils were analyzed for Olsen P (Ol), Mehlich-3 P (M3), water extractable P (WEP), and Fe-oxide coated filter paper strip P (FeO), each of which was then used to calculate manure PSC. Manure PSCM3 had the strongest linear relationships (r2=0.95–0.97) among different incubation durations, compared with PSCWEP (r2=0.79–0.91), PSCOl (r2=0.85–0.94), and PSCFeO (r2=0.88–0.91). The 2 week incubation yielded PSCM3which had the strongest linear relationships (r2=0.87–0.97 with a mean of 0.95) among the tested soils, compared with those from 2-d, 8-week, and 26-week incubations. In addition, laboratory PSCM3 had the strongest linear relationships with those PSCM3 measured under field conditions, relative to PSCOl, PSCFeO, and PSCWEP. Hence, the 2-week incubation along with Mehlich-3 P yielded the most consistent PSCs for various manures across soil types, incubation durations, and soil conditions, and can be recommended as a common protocol for determining manure PSC. The recommended default PSC values are 110, 65, 46, and 43% for liquid swine, liquid dairy, solid poultry, and solid beef manures, respectively, for the new P index of Ontario.

Potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment

All life forms require phosphorus (P), which has no substitute in food production. The risk of phosphorus loss from soil and limited P rock reserves has led to the development of recycling P from industrial residues. This study investigates the potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment (ASH DEC) in Finland. An ASH DEC plant could receive 46–76kt/a of sewage sludge ash to produce 51–85kt/a of a P-rich product with a P2O5 content of 13–18%, while 320–750kt/a of manure ash could be supplied to produce 350–830kt/a of a P-rich product with a P content of 4–5%. The P2O5 potential in the total P-rich product from the ASH DEC process using sewage sludge and manure ash is estimated to be 25–47kt/a, which is significantly more than the P fertilizer demand in Finland’s agricultural industries. The energy efficiency of integrated incineration and the ASH DEC process is more dependent on the total solid content and the subsequent need for mechanical dewatering and thermal drying than on the energy required by the ASH DEC process. According to the results of this study, the treated sewage sludge and manure ash using the ASH DEC process represent significant potential phosphorus sources for P fertilizer production.

Soil phosphorus status and environmental risk of phosphorus run-off from pastures in south-eastern New South Wales

Soils were sampled from 136 sites representing the major soil types in the Sydney drinking water catchments to provide an overview of agronomic phosphorus requirement and phosphorus environmental risk for the various pastoral land uses, which together comprise 40% of the 15700-km2 catchment area. Critical values for Colwell P (estimated from the phosphorus buffering index) were subtracted from the measured Colwell P to derive a ‘normalised’ Colwell P for each site, with negative values broadly signifying potential agronomic response and positive values warranting an assessment of environmental risk. Normalised Colwell P was above zero at approximately half the sites, and &gt;50mgkg–1 at 20% of sites that were considered to present a significant environmental risk, highlighting the need for more effective use of soil testing. Colwell P was highly variable within soil type and land use. No category could be singled out for special attention for management except for dairy and former dairy sites. Where dairy effluent must be applied to soils already high in P, a plan is needed to manage stormwater run-off. Pastures at approximately 20% of sites were ‘degraded’, where the priority should be to improve pasture management and reduce the risk of phosphorus loss in surface erosion.

Land use as an explanatory factor for potential phosphorus loss risk, assessed by P indices and their governing parameters.

The total level of phosphorus (P) and the distribution of P pools in the topsoil are significantly affected by the excessive application of mineral and organic fertilizers connected with intensive agriculture. This leads to an increased potential risk for P loss, and then contributes to freshwater eutrophication. Soil test P (STP), P sorption index (PSI) and degree of P saturation (DPS) are commonly applied as proxies for assessing the risk of P loss. Although conceptually based, the empirical relationships between these operationally defined proxies and the actual P flux exhibit large spatial variations. Herein, a comprehensive synoptic study and monitoring of soil has been conducted in a watershed in north-eastern China. A set of conventional indicators for soil P loss risk were measured along with the main P pools, P sorption indices, texture, organic matter, as well as Fe and Al oxides and other mineral compositions. Moreover, detailed soil P speciation was conducted using phosphorus nuclear magnetic resonance ((31)P NMR) spectroscopy. In addition, phosphatase activities in the soils were determined for each land use soil category. The results reflected that the soil content of total P, total inorganic P and STP increased significantly following the order of increasing management intensity. STP, being strongly coupled to the application of P fertilizers, was a strong explanatory factor for the spatial differences in DPS - both between and within different land uses. The dominant inorganic and organic P species in the soils were orthophosphate and monoester-P, respectively. Their contents were oppositely correlated with the degree of management influence, with the amount of orthophosphate positively related. Alkaline phosphomonoesterase (AlP) represented the highest activities among the four representative phosphatases, i.e. enzymes that hydrolyze organic P - releasing labile orthophosphate. Orchard soils were found to contain the highest levels of monoester P as well as high AlP activities. This indicates a strong capacity to produce labile orthophosphate. Our results suggest that the type of land use can be employed as a general explanatory factor for considering the potential high risk of loss of P. Regionalized P loss parameters will further improve the accuracy of risk assessment.

Soil phosphorus saturation ratio for risk assessment in land use systems

The risk of phosphorus loss from agricultural soils can have serious implications for water quality. This problem has been noted particularly in sandy soils in several parts of the world including Europe (e.g., the Netherlands, Italy, and UK) and the southeastern USA. However, the capacity of a soil to retain P is limited and even non-sandy soils have the potential to eventually release P when inorganic or organic fertilizer is added over a period of time. A threshold phosphorus saturation ratio (PSR), calculated from P, Fe and Al in an oxalate or a soil test solution such as Mehlich 1 or Mehlich 3, has been recognized as a practical means of determining when a soil has reached a level of P loading that constitutes an environmental risk. When soils are below a threshold PSR value, the equilibrium P concentration (EPC0) is minimal. Further, the soil P storage capacity calculated from the same data is directly linked to the strength of P bonding (KL) as determined from Langmuir isotherms, and KD, the distribution coefficient related to the strength of sorption. While the PSR is occasionally used as a predictor of the onset of environmentally significant P loss from a soil, the procedure might be adopted as a routine soil test.

A phosphorus index for use in intensive irrigated areas

AbstractIn irrigated semi‐arid areas, nutrient pollution from agriculture from irrigation return flows is one of the most important surface water quality problems and can lead to eutrophication. In this study, a new phosphorus index called IPreg has been adapted as a management tool for application to irrigated farming systems and then applied within ‘Las Filadas’ drainage basin (Spain) at a plot scale. Two new transport factors related to the irrigation management system were introduced: (i) the seasonal irrigation performance index and (ii) the efficiency of the mean irrigation dose that represents average water losses below the root zone when an average irrigation dose is applied. IPreg includes 10 factors, three of which account for P availability in the soil and seven for P transport processes. The results indicate that 18% of the study area had a high to very high risk of phosphorus loss and 60% at medium risk. Corn and alfalfa had the highest IPreg values under intense irrigation and high fertilizer application rates. IPreg was also higher in phosphorus‐rich soils and in plots treated with organic manure, especially pig slurry.

Impact of Fertilization and Soil Phosphorus Status on Phosphorus Leaching from Soil in Vegetable Greenhouse

The vegetable utilization rate of phosphorus fertilizer in greenhouse condition was low in the season of fertilizer application, resulting in phosphorus accumulation in the top soil year after year. The risk of phosphorus loss through leaching increased under the circumstance of inappropriate watering management and fertilization. In this study, leaching experiments using columns packed with a greenhouse soil with different soil phosphorus status (low, medium and high levels) were carried out under greenhouse condition to investigate the impact of fertilizer application on phosphorus leaching from greenhouse soil. The fertilization treatments included no fertilizer [CK], organic manure and chemical fertilizer [M+NPK], organic manure [M], chemical fertilizer [NPK]. The vertical migration and leaching loss of soil phosphorus were measured. Results were as follows: (1) total phosphorus (TP) content increased with the extension of leaching time. In the low-level- and medium-level-phosphorus greenhouse soils, TP concentration in the effluent increased with the application of manure; (2) In the high-level-phosphorus greenhouse soil, phosphorus in the effluent from the treatment with the use of fertilizer was the highest TP, with accumulative leaching amount of 2.85 mg in 51 days. The leaching of phosphorus became small after 36 days of leaching experiment. Our study showed that application of manure and chemical fertilizer at proper rates according to soil phosphorus status is beneficial to reduce the leaching loss of phosphorus to the environment.

Assessing the Risk of Phosphorus Loss and Identifying Critical Source Areas in the Chaohu Lake Watershed, China

Agricultural nonpoint phosphorus (P) pollution is a primary cause of eutrophication in many freshwater systems. Identifying areas that are at high risk for P loss in a watershed and concentrating management efforts on these smaller sections is a more effective method for limiting P loss than implementing general strategies over a broad area. A modified P index scheme was used to assess the risk of P loss and identify critical source areas in the Chaohu Lake watershed on a regional scale. In the new P ranking scheme, soil P sorption index (PSI) and degree of P saturation (DPS) were introduced as source factors to represent the inherent ability of P transport in the soil-water interface. Distance from P sources to Chaohu Lake was also considered as a transport factor to take into account P degradation from source to the final receiving water. The ranking scheme was modified to use available data on the regional scale. P index calculation results showed high spatial variation of P loss risk in the Chaohu Lake watershed. The highest risk areas focused on the downstream parts of the main rivers that discharge into Chaohu Lake. The induction of new components into the P index calculation makes it possible to identify critical source areas of nonpoint P loss on a regional scale, thus allowing decision makers to implement best management practices (BMPs) in such a manner as to minimize P loss to sensitive watercourses.

Indicator for Risk of Phosphorus Loss from Sandy Soils

SL333, a 3-page illustrated fact sheet by Vimala D. Nair, Willie G. Harris, and Debolina Chakraborty, describes a practical means of determining when a soil has reached a level of P loading that constitutes an environmental risk. Includes references. Published by the UF Department of Soil and Water Sciences, October 2010. SL333/SS539: An Indicator for Risk of Phosphorus Loss from Sandy Soils (ufl.edu)

Sensitivity of soil phosphorus tests in predicting the potential risk of phosphorus loss from pasture soil

The objective of this study was to examine the effects of urine and dung additions on the phosphorus (P) chemistry of pasture land and to compare the sensitivity of two soil extraction methods in assessing the P-loading risk. In a field experiment, urine and dung were added to soil in amounts corresponding to single excrement portions and the soil samples, taken at certain intervals, were analysed for pHH2O, acid ammonium acetate extractable P (PAc) and water extractable total P (TPw), and molybdate reactive P (MRPw). Urine additions immediately increased soil pH and MRPw, but no such response was observed in PAc extraction due to the low pH (4.65) of the extractant enhancing the resorption of P. The PAc responded to the dunginduced increase in soil total P similarly as did Pw, which suggests that both tests can serve to detect areas of high P concentration. However, water extraction was a more sensitive method for estimating short-term changes in P solubility. In pasture soils, the risk of P loss increases as a result of the interaction of urination and high P concentration in the topsoil resulting from continuous dung excretion.;

The effects of manure application on soil aggregation

Surface application of manure may increase the risk of phosphorus loss in runoff. Manure application, however, often results in increased soil aggregate stability with reduced runoff and erosion and, therefore, reduced P transport potential. Three field studies were conducted with silt loam or silty clay loam soil in Nebraska to determine how water- stable soil aggregation in the 0- to 25-mm soil depth is affected: (1) by application of raw or composted feedlot manure; (2) by repeated annual manure application; and (3) by the residual effect of composted manure applied five to seven years before sampling. Large macro-aggregates ((2 mm) were increased 200% or more by both manure and compost application within 15 days after application; the effect persisted for the seven months of study with a greater effect due to compost application. Aggregate stability was similar for incorporation and no incorporation of the applied compost or manure. Bray-P1 in large macro-aggregates was 200% more than for the whole soil sample with manure or compost applied, but Bray-P1 in large macro-aggregates was similar to the whole sample in the control. Annual application of swine slurry for several years resulted in a 20% increase in aggregates (250 mm. After four years of no compost following three years of compost application, aggregate size distribution was similar for the compost- compared to the no-compost-applied treatments. Increased macro- aggregate formation and high Bray-P1 in these aggregates may protect against P loss in runoff due to reduced runoff and erosion and protection of P in water-stable large macro-aggregates.

Environmental Index for Estimating the Risk of Phosphorus Loss in Calcareous Soils of Manitoba

The degree of phosphorus saturation (DPS) has been used in evaluating the risk of P loss from soil to runoff. While techniques are available for calculating DPS for acid soils, no widely used technique exists for neutral to calcareous soils that are typical of the Northern Great Plains, including Manitoba (Canada) soils. This study aimed to develop techniques of calculating the DPS of neutral to alkaline soils. Four measures of soil labile P and ten indices of P sorption capacity were used to calculate the DPS of 115 Manitoba soils. The various DPS calculated were evaluated using water-extractable ((H2O)) P as an index of P susceptibility to runoff loss. The DPS obtained using Olsen-extractable ((Ols)) P and the Langmuir adsorption maximum (ES(max)) ranged from 0.5 to 31.9% while those obtained from P(Ols) and the single-point adsorption index (P(150)) ranged from 0.9 to 73.9%. Of all the DPS evaluated, those that included P(Ols) and Mehlich 3-extractable ((M3)) P as the numerator with either P(150) or ES(max) as the denominator were fairly well correlated with P(H2O) (r values ranged between 0.45 and 0.63). Along with ES(max) and P(150), a new method of calculating DPS was formulated as the ratio of P(Ols) or P(M3) to Ca(M3) or (Ca + Mg)(M3). We found that the ratio of ammonium oxalate-extractable ((ox)) P to (Al + Fe)(ox), which has been widely used to calculate DPS in acid soils, was not suitable for neutral to alkaline soils of Manitoba. In these neutral to alkaline soils, Ca(M3) or (Ca + Mg)(M3) were better indices of P sorption capacity while P(Ols) and P(M3) provided better estimates of labile soil P. The DPS calculated using Ca(M3) or (Ca + Mg)(M3) were well correlated with P(H2O); however, they were numerically smaller than those obtained from the Langmuir adsorption maximum. As such, a saturation coefficient (alpha) with a value of 0.2 was generated to improve the numerical values of the newly estimated DPS. This new approach can be used to estimate the DPS in neutral and calcareous soils without the need to generate a P adsorption maximum.

Modelling phosphorus losses from pastoral farming systems in New Zealand

A model was developed for incorporation into the computer model “Overseer® nutrient budgets 2” to estimate phosphorus loss from pastoral farms to surface waters. The model sums potential risk of phosphorus loss from soil (background) with incidental losses attributed to the application of fertiliser or effluent to fields or waterways. The overall risk is estimated as the amount of P lost annually (kg P ha–1 yr–1). Data for 23 sites of grazed pasture (sheep, beef, and dairying) ranging from small plot trials to catchments were used to validate each component of the model. A good relationship (R2 = 0.97***) was obtained between measured and estimated soil P losses for systems without much incidental P loss. Similarly, a good relationship was observed between measured and estimated overall (soil + incidental) P losses for all systems (R2 = 0.96***). The estimated loss of P is categorised into low, medium, high or extreme risk to the environment (<1, 1–2, 2–4, and >4, respectively) and best management strategies are suggested accordingly. The model shows promise in directing responsible P management for New Zealand pastoral farms. However, inadequacies are likely when scaling up the model for use in large catchments where land use and soils vary greatly.

Scaling issues relating to phosphorus transfer from land to water in agricultural catchments

Various scales of input data exist to parameterise diffuse pollution models for the UK. For screening methodologies such as the phosphorus indicators tool—PIT [Heathwaite, A.L., Sharpley, A.N., Bechmann, M., 2003a. The conceptual basis for a decision support framework to assess the risk of phosphorus loss at the field scale across Europe. Journal of Plant Nutrition and Soil Science 166, 1–12; Heathwaite, A.L., Burke, S., Quinn, P.F., 2003b. The nutrient export risk matrix (the NERM) for strategic application of biosolids to agricultural land. International Association for Hydrological Sciences Publication 285, 1–9], which is applied throughout England and Wales, some assessment of the implications of using input data derived at different scales must be made. This work is further driven by practical issues such as licensing costs and data availability, which mean that not all data are readily accessible for all end users. This paper represents a first step towards quantifying the ‘value-added’ to model predictions by using input data derived at three different scales: 50×50 m, 1×1 km and 5×5 km. Model runs using PIT were carried out against observed phosphorus water quality data from the River Start and River Gara, which are the main sub-catchments of Slapton Ley, a grade 1 National Nature Reserve in southwest England. Model runs for the main 46 km 2 Slapton catchment were also undertaken. The results show that some improvement in the ability of the model to capture the observed water quality behaviour may be made by using higher resolution DEM data, though these improvements may be outweighed by the extra data processing and computational time. Conversely, model runs driven by the 5 km data demonstrate consistent under-prediction for all three test catchments, which is perhaps not surprising given the greater degree of averaging underlying datasets at this scale. Results from the 1 km datasets provide the best agreement with observed water quality data, and appear to provide the ‘best available’ means of parameterising PIT at the national scale.

The conceptual basis for a decision support framework to assess the risk of phosphorus loss at the field scale across Europe

AbstractWe report a conceptual framework for a simple screening tool to evaluate the vulnerability of different fields in the landscape to phosphorus (P) loss within the European agricultural context. Our work builds on the principles established for the P Index system developed in the United States. We examine the differing needs and criteria for a range of EU member states and EFTA countries and highlight essential and optional criteria for inclusion in the decision support framework depending on their ecoregional characteristics. A framework such as this, meets in principle, the needs of the COST832 Action ‘Quantifying the Agricultural Contribution to Eutrophication’ as it deals with diffuse nutrient sources from agriculture, and aids more targeted use of practical strategies to mitigate nutrient losses to minimise the potential for the eutrophication of receiving waters.